At the top of a looped section of roller coaster track, the car and rider are completely upside down. Engineers calculated that the car may travel a minimum speed of 14.3 m/s to keep riders from falling out of the car at the top of the loop. What is the radius of the loop? 22.5 m 18.9 m 17.4 m 20.9 m

Two masses are connected by a rope that hangs over a pulley as shown below. the pulley is a uniform cylinder of radius 푅=0.381meters and mass 푀=3.1푘푔. initially 푚"is on the ground and 푚#rests 2.5 meters above the ground. if the system is released, use conservation of energy to determine the speed of 푚#just before it strikes the ground. assume the pulley bearing is frictionless.